Apparatus for cooling a refrigeration system motor



Sept 1, 1964 s. J. RACHFAI. ETAL 3,146,605

APPARATUS FoR cooLING A REFRIGRRATION SYSTEM MoToR A Filed June 2, 1961 E llllllllllllulllllll:I

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INVENTORS STANLEY J. RACHFAL LAWRENCE MACROW AWM ATTORNEY.

United States Patent O APPARATUS FOR COOLING A REFRIGERATION SYSTEM MOTOR Stanley J. Rachfal, Syracuse, and Lawrence Macrow, Fayetteville, NX., assignors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed June 2, 1961, Ser. No. 114,373 4 Claims. (Cl. 62197) for both the compressor and the motor for driving the compressor. Various arrangements have been provided for the purpose of cooling the motor, among the more prominent of which are water cooled jackets and piping for utilizing refrigerant gas formed in the evaporator or in the economizer; in machinery having an economizer feature, as a cooling medium.

With the advent of improved materials and methods of insulating the electric conductors employed in a hermetic motor, it has been found feasible to utilize liquid refrigerant as a cooling medium. This invention contemplates an improved arrangement for utilizing liquid refrigerant as a cooling medium for a motor in a hermetic motor-compressor unit employed in a refrigeration system.

The chief object of this invention is the provision of apparatus for efficiently cooling a motor of the kind under consideration wherein liquid refrigerant from the refrigeration system is used as a cooling medium.

Another object of this invention is theprovision of novel means for distributing liquid refrigerant within the housing or casing enclosing a motor in a motor-compressor unit.

A still further object of the invention is the provision of a novel means of cooling a hermetic motor wherein liquid refrigerant from a refrigeration system is employed as the cooling medium.

Another object of the invention is the provision of a novel rotor construction for use in a motor cooled by liquid refrigerant from a refrigeration system wherein the motor is used to drive a compressor employed in the system.

These and other objects of the invention will be apparent upon a consideration of the ensuing specification and drawings in which:

FIGURE 1 is a diagrammatic view of a refrigeration machine employing a motor cooling arrangement forming the subject of the invention; and

FIGURE 2 is a diagrammatic view of a portion of a refrigeration system illustrating a modification of the invention.

Referring to FIGURE 1 of the drawings for an illustration of a first embodiment of the invention, there is shown a refrigeration system employing a motor-compressor unit 10 forwarding compressed refrigerant gas at high pressure through line 13 to a condenser 14 for liquefaction. The motor compressor unit 10 includes a housing forming a first compartment 11 accommodating an impeller of a centrifugal compressor and a second compartment 12 accommodating a motor having a drive shaft coupled to an impeller drive shaft through a gear reduction unit.

aimes j Patented Septfl, 1964 ice From the condenser 14, liquid refrigerant flows through an expansion chamber 15 employed to meter the flow of liquid refrigerant to the evaporator 17 through line 16.

ln the evaporator, the liquid refrigerant is changed to the gaseous state and flows through suction line 18 to the inlet of the compressor. The inlet of the compressor is provided with guide vanes 19 located forwardly of impeller wheel 20 for the purpose of regulating the capacity of the machine.

In the condenser, gaseous refrigerant is converted to the liquid phase as it passes in heat transfer relation with a cooling medium such as water owing in coil 21. Coil 21 is part of a system not shown, which includes a cooling tower wherein the heat of condensation is rejected and the water returned to coil 21 for subsequent passage through the condenser.

Coil 22, disposed in evaporator 17, is part of a closed circuit designed for the purpose of providing relatively cool water to areas where cooling is required. Water flowing in coil 22 is cooled as heat is extracted therefrom by the vaporizing refrigerant. The system described is conventional and is used in'refrigeration equipment employed in air conditioning systems. The particular details of the system described may be varied within limits well known to those familiar with air conditioning plants to provide equipment similar in function to that described.

Line 35 is shown connected to condenser 14 to provide a passage for liquid refrigerant to the interior of the compartment 12 enclosing the motor assembly employed to drive the compressor. The motor assembly includes a stator 23 positioned within the interior of the casing forming the compartment 12 and a rotor 24 fixed to drive shaft 25 mounted in suitable bearings disposed in the end cover 24' and partition 25 of the motorcompressor unit 10. Located forwardly of thepartition 25 is the gear reduction assembly which in turn is connected, as described above, to the impeller 20. Suitable seals are provided for the purpose of preventing'escape of high pressure refrigerant gas into the portion of the housing accommodating the motor.

The rotor and stator members are provided with passages 26 and 27 extending therethrough for a purpose to be later described. End windings 29 of the coils of electrical conducting material forming a part of the stator assembly, are shown projecting from the extremities of the stator. The usual clearance space 28, between the rotor and stator members is also shown.

Line 35 is shown extending into the interior of the housing and terminating adjacent rotor 24. It is to be noted that rotor 24 is provided with axially extending members 30 connected to the motor end ring and more aptly described as blades arranged in circumferentially spaced relation about the rotor. For the purpose of extracting refrigerant vaporized by heat transfer with the components of the motor assembly, there is provided line 38 connected to evaporator 17.

The flow of liquid refrigerant in line 35 is under the control of a thermal expansion valve 40 including a capillary bulb 41 positioned on the motor casing or in the motor windings and having communication through capillary 42 with the power element, not shown, of the valve member. In order to assure a constant supply of flow through the housing, the valve body of the thermal expansion valve assembly may be provided with a small passage therethrough.

Considering the operation of the apparatus described, liquid refrigerant from the high pressure side of the refrigeration apparatus flows through line 35 into the interior of the portion of the casing housing the motor driving the compressor. The end of the line terminating in the interior of the housing is located adjacent the axial extensions or blades 30 secured to the rotor member.

Liquid refrigerant from the high pressure side of the system owing into the compartment 12 contacts the rotating blade members and is partially atomized and partially vaporized. The refrigerant gas, together with entrained unvaporized liquid, iiows throughth'e passages provided' in the rotor and stator member. Circulation of refrigerant gas and liquid through the openings' 26 and 27 is accomplished through a path dened by the arrows shown in FIGURE 1. The blades .30 propel the refrigerant radially outwardly while creating a zone of low pressure inthe passages 27 in communication with the space radially inward of the blades. The action is similar to that involved in the centrifugal blower type fan. Extraction of heated vapor from the motor compartment is accomplished by the action of the impeller through suction line 18, evaporator 17 and line 38. Thus it will be appreciatedv that the interior of compartment 12 is subject to suction pressure. This has the added advantage of causing portions of the relatively high pressure liquid refrigerant to vaporize and cool down the remaining portions entering the motor housing from line 35. It has been found that during operation of the motor-compressor unit, an adequate cooling effect is obtained with the construction shown and descrbed.` 4 l Referring more particularly to FIGURE 2 wherein a second embodiment of the invention is illustrated, the valve controlling ilow of liquid refrigerant into the housing and extraction of vapor refrigerant therefrom is located in the line 38 downstream of the motor assembly. Thus the flow of refrigerant through line 35 to the motor compartment and into the evaporator is under the con-` trol ofa valve located in the low pressure side of the machine. FIGURE 2 is identical to that illustrated in FIGURE 1 with the exception that flow of motor cooling medium is controlled by a valve 40 located in line 38. As noted above, valve 40 has an opening therethrough permitting Operation` of the embodiment illustrated in continuous Acommunication between the motor casing and the evaporator. While we have described a preferred embodiment of the invention, it wil-l be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. Refrigeration apparatuscomprising a compressor; a motor for driving said compressor, said motor includingy a rotor having circumferentially spaced blades extending axially from one end thereof, a stator and a housing, said Vrotor and stator being provided with longitudinal passages extending therethrough; a condenser; an evaporator; refrigerant metering means interposed between said condenser and evaporator; a linevfor transl mitting liquid refrigerant formed in the high pressure side of the refrigeration apparatus to the interior of said housing to cool the rotor and stator, said line terminating within said housing adjacent the spaced blades so that liquid refrigerant delivered to the interior of the housing will be atomized by the action of the blades for flow through said rotor and stator passages and means for returning refrigerant to the refrigeration apparatus after passage through said rotor and stator passages, said means including a line connecting the interior of the housing and the system and means interposed in said last-mentioned line regulating flow of refrigerant therein.

2. Refrigeration apparatus having a low pressure side` and a high pressure side comprising a compressor; a motor for driving said compressor, said motor including a rotor having circumferentiallyy spaced blade means extending axially from one end thereof at the outer periphery thereof, a stator surrounding said rotor in spaced relation thereto and a housing, said rotor andstator being provided with internal longitudinal passages, remote from and lindependent of saidv space between said rotor and said stator, extending therethrough; a condenser an evaporator; refrigerant metering means interposed between said condenser and evaporator; and a line for transmitting liquid refrigerant formed in the high pressure side of the refrigeration apparatus to the interior of said housing Ato cool the rotor and stator, said line terminating within said housingadjacent the spaced blade means so that liquid refrigerant delivered to the interior of the housing will b`e atomized bythe action of the blade means for flow under elevated pressure through said stator passages yand will How through the rotor passages under reduced pressure created by said blademeans and means for returning refrigerant flowing through said passages to the low pressure side of the apparatus.

3'. ARefrigeration apparatus as described in claim 2 wherein valve means for regulating flow of liquid refrigerant'are disposed in the line transmitting liquid refrigerant to theinterior of the casing.

4. Refrigeration apparatus as described in claim 2 wherein said last mentioned means includes a valve for regulating flow of refrigerant tothe low pressure side of themachine.

References Cited in the le of this patent vUNITED STATES PATENTS Moody May 22, 1956 v2,793,506 Moody May 28, 1957 3,088,042 Robinson a Apr. 30, 1963 'FOREIGN PATENTS 1,232,820 France Apr. 25, 1960 

1. REFRIGERATION APPARATUS COMPRISING A COMPRESSOR; A MOTOR FOR DRIVING SAID COMPRESSOR, SAID MOTOR INCLUDING A ROTOR HAVING CIRCUMFERENTIALLY SPACED BLADES EXTENDING AXIALLY FROM ONE END THEREOF, A STATOR AND A HOUSING, SAID ROTOR AND STATOR BEING PROVIDED WITH LONGITUDINAL PASSAGES EXTENDING THERETHROUGH; A CONDENSER; AN EVAPORATOR; REFRIGERANT METERING MEANS INTERPOSED BETWEEN SAID CONDENSER AND EVAPORATOR; A LINE FOR TRANSMITTING LIQUID REFRIGERANT FORMED IN THE HIGH PRESSURE SIDE OF THE REFRIGERATION APPARATUS TO THE INTERIOR OF SAID HOUSING TO COOL THE ROTOR AND STATOR, SAID LINE TERMINATING WITHIN SAID HOUSING ADJACENT THE SPACED BLADES SO THAT LIQUID REFRIGERANT DELIVERED TO THE INTERIOR OF THE HOUSING WILL BE ATOMIZED BY THE ACTION OF THE BLADES FOR FLOW THROUGH SAID ROTOR AND STATOR PASSAGES AND MEANS FOR RETURNING REFRIGERANT TO THE REFRIGERATION APPARATUS AFTER PASSAGE THROUGH SAID ROTOR AND STATOR PASSAGES, SAID MEANS INCLUDING A LINE CONNECTING THE INTERIOR OF THE HOUSING AND THE SYSTEM AND MEANS INTERPOSED IN SAID LAST-MENTIONED LINE REGULATING FLOW OF REFRIGERANT THEREIN. 